This invention relates to an adaptor plate for a semiconductor tester.
A semiconductor tester typically includes a test head and pin electronics circuits mounted in the test head. A load board is attached to the test head and provides part of an electrical interface between terminals of a device under test (DUT). A semiconductor tester can be used in conjunction with a device handler for testing packaged devices. In this case, the test head is typically positioned beneath the handler with the load board in a horizontal plane and the test head is moved in a horizontal (XY) plane to position a receptacle attached to the load board vertically below a socket attached to the handler. The test head is then moved vertically upwards (along the Z axis) to engage the receptacle with the socket. When the socket and receptacle are properly engaged, the handler delivers devices to be tested to the socket, and the socket and receptacle provide an electrical interface between the DUT and the pin electronics circuits.
In order to avoid damage due to collision between the socket and receptacle, upward vertical movement of the test head relative to the handler must be positively limited. Hitherto, in order to provide a positive stop for limiting upward movement of the test head relative to the handler, the test head has been provided with an adaptor plate that is disposed horizontally and is formed with an opening through which the load board is exposed. The adaptor plate is secured to the test head and rests against a Z axis abutment or shoulder at a predetermined position relative to the upper surface of the load board. The thickness of the adaptor plate is selected so that when the test head is in the proper vertical position relative to the handler, the upper surface of the adapter plate is in contact with the bottom of the handler.
Frequently, a given tester is designed so that it can be used in conjunction with several different handlers. From handler to handler, the vertical position of the socket relative to the bottom of the handler can vary. Further, the dimensions of the socket and receptacle depend on the particular device being tested, and so the height of the socket and receptacle when engaged can vary from device to device. Consequently, the height of the upper surface of the load board relative to the bottom of the handler can vary from handler to handler and from device to device. This has hitherto necessitated that potentially a different adaptor plate is needed for each combination of handler and device. The adaptor plates are bulky and are expensive to manufacture and furthermore it is time consuming and inconvenient to have to change the adaptor plate each time the tester is used with a different handler or for testing a different device.